The present invention relates to a method and an apparatus for estimating an RMS current of an intermediate-circuit capacitor for an overall system made up of a battery, an inverter, and an electric machine.
In hybrid and electric vehicles, inverters or pulse-controlled inverters are used for driving the electric machines. It is not only for monitoring purposes that knowledge about a so-called RMS current of an intermediate-circuit capacitor is desirable.
The known concepts for calculating the RMS current or the intermediate-circuit capacitor perform analytical calculations which, however, apply only to specific driving methods or pulse patterns of the inverter. The known concepts therefore provide no option for calculating the RMS current of the intermediate-circuit capacitor for any arbitrary driving methods and operating points of the inverter and the electric machine.